I. Field of the Invention
This invention relates to a hydraulic packer assembly which is set in a casing of an oil or gas well. More particularly, the present invention relates to a hydraulic packer assembly comprising a packer and a setting tool, which packer is secured and sealed to the casing by a fluid pressure passing through a tubing string and into the setting tool.
II. Description of the Prior Art
In an oil or gas well, the annular space or annulus between the tubing string and the well casing is sealed by a packer. The packer causes the fluid being pumped, e.g., oil, from the earth cavity penetrated by the casing to flow within the tubing string and not between the tubing string and the well casing. Conventionally, the packer is mounted on a setting tool, which setting tool is coupled to the end of a tubing string, or on an electric cable that is lowered into the well casing. Once the packer is located at the appropriate depth within the well casing, suitable mechanisms are actuated securing and sealing the packer to the inner surface of the well casing, thereby sealing the annular space between the tubing string and well casing.
One conventional system for setting and sealing the packer within the well casing is electrically operated. Such system requires rigging and feeding an electrical line and packer assembly through the well casing from the surface. However, the electrical lines are expensive and are difficult and time consuming to feed through the casing. Additionally, packers set with electrical lines create additional risk and expense by requiring swabbing or jetting of the well with nitrogen when bringing the oil or gas well on production. Expensive rig time is also used while landing the tubing string in the packer, and when swabbing or jetting the well with nitrogen.
Conventional mechanical and hydraulic packers also experience difficulties. Such packers have not permitted relative movement between the tubing and the packer causing large amounts of stress on both the tubing string and the packer. Additionally, such packers have failed when the formation is stimulated or the tubing string is subjected to high fluid pressure. Moreover, the mechanical packers require weight to be set on the packer which can deform the tubing string and hinder the passage of wireline tools. Typical examples of conventional hydraulic packers are disclosed in U.S. Pat. No. 3,112,796 to Myers and U.S. Pat. No. 3,211,227 to Mott, the disclosures of which are hereby incorporated by reference.
Each of the conventional packer systems has its own advantages and disadvantages. Thus, a packer is needed which will combine the advantages normally associated with mechanically, electrically and hydraulically operated systems, without their normally attendant disadvantages.